1. Field of the Invention
The present invention relates in general to a reclining device for a seat, and more particularly to a power reclining device for an automotive seat.
2. Description of the Prior Art
Hitherto, various power reclining devices have been proposed and put into practical use.
As is known, the power reclining device is a device for adjusting the angular position of a seatback relative to a seat cushion by the power, for example, of an electric motor to provide a seat occupant with a comfortable sitting posture.
Some of the power reclining devices are of a type which comprises two base plates, two pivoting arms, a flat spiral spring, an electric motor unit and a connecting shaft.
In the power reclining device of this type, the base plates are respectively secured to laterally opposed side rear portions of the seat cushion. The pivoting arms are respectively secured to laterally opposed side lower portions of the seatback. Each pivoting arm is pivotally connected to the corresponding base plate through a rotating shaft. Thus, the base plates and the pivoting arms constitute laterally spaced hinge units. The connecting shaft is secured at its longitudinal opposed ends to the rotating shafts to achieve integral rotation therebetween. The electric motor unit is operatively connected to one of the rotating shafts. A reduction gear mechanism is arranged between each pivoting arm and the corresponding base plate, and engaged operatively with the rotating shaft. By energizing the electric motor unit, both rotating shafts are forced to turn in one direction. With this, each reduction gear mechanism is actuated. Then, the pivoting arms pivot about the rotating shafts and thus rotate the seatback forward or rearward relative to the seat cushion. The flat spiral spring has an inner end secured to the base plate and an outer end secured to the pivoting arm. Therefore, the flat spiral spring biases the seatback rearward or forward relative to the seat cushion. The flat spiral spring is disposed on the outboard side of the hinge unit because the rotating shaft interferes with the flat spiral spring in disposing the flat spiral spring on the inboard side of the hinge unit.
Thus, the flat spiral spring extends outwardly from the hinge unit. Therefore, the power reclining device of this type becomes relatively large in size and may interfere with other vehicular parts in disposing those parts close to the reclining device.